Contact Information

Short Biography

Professor Kaner received his Ph.D. in Chemistry in 1984 from the University of Pennsylvania. He is also a member of the following professional societies: Fellow of the American Association for the Advancement of Science; Associate Editor for Materials Research Bulletin; member of the American Chemical Society; the Electrochemical Society; and the Materials Research Society.

Research Interest

1. Conducting Polymers:

Kaner group is interested in all aspects of conducting polymers, ranging from the fundamental science of these materials to their development for a wide variety of applications. The information provided here is a small glimpse into our research.

Nanostructured conducting polymers possess many advantageous properties over conventional, bulk counterparts. Since the properties of nanomaterials are highly dependent on their size, shape, and alignment over a macroscopic area, controlling these factors for nanoscale conducting polymers is of great importance. The Kaner group is interested in controlling these parameters without the aid of traditional external templates such as surfactants or nanoporous membranes. This process exploits the fact that conducting polymers have a predisposition to form certain nanoscale shapes under specific synthetic conditions. Ultimately, the goal is to develop a methodology that can produce conducting polymers of virtually any nanoscale size or shape. From this, we can begin to investigate morphology-property relationships and to integrate these new materials into devices.

Applications:

1. Composite Materials of Conducting PolymersConducting polymers can be used as a platform to create polymer/organic or polymer/inorganic composites. These composite materials often exhibit enhanced properties or superior device performance as compared to pure conducting polymers. For example, composite materials of polyaniline/metal nanoparticles can be fabricated by exploiting the simple redox chemistry of polyaniline. The composites are a highly effective material in a wide variety of applications such as chemical sensors, molecular memory, or catalysis.

2. Chemical SensorsThe development of high-performance chemical sensors is receiving increased interest due to its importance in environmental protection and homeland security. We have demonstrated that polyaniline nanofibers exhibit superior sensing performance compared to bulk films, indicating that conducting polymer nanofibers are good candidates for chemical sensing. A systematic investigation into the response of conducting polymer nanofibers to a series of toxic industrial gases and chemical is currently under investigation.

3. Memory Devices and High Density Electronics (in Collaboration with Prof. Yang Yang)Using the decorated nanofibers as an active layer sandwiched between two aluminum electrodes, we have recently discovered that Au/polyaniline nanofibers possess a remarkable property--electrically switchable bistability, which is ideal for nonvolatile, flash memory devices. The device can be switched from the off- to the on- state at ≥3V with a switching time of ~15 nanoseconds. This produces an abrupt increase in current of more than three orders of magnitude. The device can be switched back to the off-state at ≤-5 V. The device is stable in both states and switching between these two states can be repeated numerous times without any obvious decay. In this project, we will explore the important features of this material and then seek to develop a prototype high-density, high-performance nonvolatile/flash memory circuit.

4. Actuators (in Collaboration with Qeibing Pei)For decades, engineers who build actuators (motion-generating devices) have sought an artificial equivalent of muscle. Simply by changing their length in response to nerve stimulation, muscles can exert controlled amounts of force sufficient to blink an eyelid or hoist a barbell. During the last fifteen years

5. Graphene:The Kaner group has a large research effort in a new and exciting material called graphene. Interest in graphene stems from a number of extraordinary properties including high charge carrier mobility, thermal conductivity, and mechanical strength. These are primarily the result of high symmetry and high crystal quality in graphene’s two-dimensional lattice of sp2 hybridized carbon. Our interests range from new syntheses to graphene-based devices for the next generation of integrated circuits and solar cells.

Solution Processing of Chemically Derived Graphene -Our group helped to pioneer the first solution-based method for the large-scale production of graphene. Through a process of oxidation and exfoliation of graphite, we are able to create stable dispersions of single sheets that can be reduced back to graphene before deposition. This gives us research access to large graphene flakes without the need for the laborious mechanical exfoliation techniques often employed by other researchers.

6. Transparent Conductors

Optical-electronic devices including LEDs and solar cells have become an important part of reducing power consumption and a reliance on fossil fuels. One of the most challenging part of engineering such devices is the top electrode, which must be both conductive enough to pass current and transparent enough to allow photons in or out of the device. Currently, the industry standard for transparent conductors is indium tin oxide (ITO), which is capable of less than 100 ohms/square at 90% transmittance in the visible range. However, ITO has several limitations that may preclude its widespread use in the near future. These include brittleness and the need for vacuum-based deposition. Graphene may offer a highly scalable and cheap substitute, especially because each layer absorbs just 2.3% of incident light. While this work continues with great intensity, our first efforts yielded graphene-based transparent films with resistivity less than 1000 ohms/square at 90% transmittance.

7. Superhard Materials:Superhard materials are used in many applications, from cutting and polishing tools to wear-resistant coatings. Diamond remains the hardest known material, despite years of synthetic and theoretical efforts to improve upon it. Designing new superhard materials are not only of great scientific interest, but also could be very useful. The Kaner group in collaboration with the Tolbert group has demonstrated that valence electron density and bond covalency can be used as design parameters for creating superhard, ultra-incompressible materials. Using these design parameters we have synthesized both hard and superhard materials.

8. Thermoelectric materials:Thermoelectric based devices convert a temperature gradient into power (Seebeck effect) or generate a temperature gradient upon electrical input (Peltier effect). (insert graphic on TE effects). In order to gauge the thermal to electric efficiency of a material, the The dimensionless thermoelectric figure of merit (ZT) is used and is given by ZT = S2T/ρλ. Where, S, is the Seebeck coefficient, ρ, is the electrical resistivity, T is the absolute temperature, and λ, is the thermal conductivity. Since the three terms are interdependent (any change in one parameter will affect the others), for the past 50 years, the average ZT over the entire temperature range has remained stagnant at a ZT of 1. It has been theorized that nanoinclusions could enhance ZT by reducing the thermal conductivity via interface scattering. Recent experimental work at UCLA, in collaboration at the Fleurial-Caillat group at the Jet Propulsion Laboratory in Pasadena, CA and Dresselhaus-Chen group at MIT demonstrates that similar effects can be achieved in densified nanoscale bulk materials via sintering of large scale quantities of nanostructured materials.